EP2999304A1 - Plaque de cuisson à induction et procédé pour faire fonctionner une telle plaque - Google Patents

Plaque de cuisson à induction et procédé pour faire fonctionner une telle plaque Download PDF

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Publication number
EP2999304A1
EP2999304A1 EP14185260.8A EP14185260A EP2999304A1 EP 2999304 A1 EP2999304 A1 EP 2999304A1 EP 14185260 A EP14185260 A EP 14185260A EP 2999304 A1 EP2999304 A1 EP 2999304A1
Authority
EP
European Patent Office
Prior art keywords
pulse duration
induction
enabling signal
induction hob
switching element
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP14185260.8A
Other languages
German (de)
English (en)
Inventor
Alex Viroli
Laurent Jeanneteau
Massimo Nostro
Massimo Zangoli
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Electrolux Appliances AB
Original Assignee
Electrolux Appliances AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
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Application filed by Electrolux Appliances AB filed Critical Electrolux Appliances AB
Priority to EP14185260.8A priority Critical patent/EP2999304A1/fr
Priority to EP15176589.8A priority patent/EP2999307B1/fr
Publication of EP2999304A1 publication Critical patent/EP2999304A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/06—Control, e.g. of temperature, of power
    • H05B6/062—Control, e.g. of temperature, of power for cooking plates or the like

Definitions

  • the present invention relates generally to the field of induction hobs. More specifically, the present invention is related to an induction hob configured to reduce acoustic noise during start-up of power stage.
  • Induction hobs for preparing food are well known in prior art.
  • Induction hobs typically comprise at least one heating zone which is associated with at least one induction element.
  • the induction element is coupled with electronic driving means comprising a switching element for driving an AC current through the induction element.
  • Said AC current generates a time varying magnetic field.
  • the switching element receives a pulsed enabling signal in order to enable a current flow through the induction element according to the enabling signal.
  • the current flowing through the induction element may be significantly higher than after a certain operating time of powering the power stage. Said increased switch-on current may lead to significant acoustic noise which might be disturbing for a user of the induction hob.
  • the invention relates to an induction hob comprising a power stage with at least one switching element for enabling an alternating current flow through an induction element and a control unit providing an enabling signal comprising pulses with a variable pulse duration to the switching element for enabling said alternating current flow through said induction element.
  • the pulse duration of the pulses is changed between a minimum value and a maximum value in order to adjust the power provided to the induction element.
  • Said minimum value and maximum value may be nominal minimum and maximum values defining a nominal range of pulse duration values.
  • the control unit is adapted to reduce the pulse duration of a set of enabling signal pulses to a reduced pulse duration lower than said minimum value when starting the heating process in order to reduce acoustic noise.
  • the Applicant found out that the acoustic noise can be significantly reduced by upper-mentioned reduction of pulse duration without any significant lowering of the lifetime of the switching element, although the switching element is driven in hard switching region due to the reduced pulse duration, i.e. there are hard voltage/current transitions within the switching element in the switching moment.
  • acoustic noise can be avoided or reduced without any additional circuit components for reducing said acoustic noise.
  • the switching element is an insulated-gate bipolar transistor.
  • Said insulated-gate bipolar transistor may be arranged in a quasi-resonant architecture.
  • the power stage comprises a quasi-resonant architecture comprising a single switching element.
  • there is no further switching element needed which may reduce the acoustic noise by lowering the charge of a capacitor providing electric power to the induction element.
  • the pulse duration is reduced during a first set of half-waves of mains provided by a bridge rectifier to the power stage immediately after start-up of the power stage.
  • the electric charges accumulated at a capacitor are significantly reduced. Therefore, also the current provided to the induction element is significantly decreased.
  • the power stage may be driven within the nominal range of pulse duration, i.e. with a pulse duration between minimum pulse duration and maximum pulse duration because the risk of causing acoustic noise is eliminated during the period of said first set of half-waves.
  • the first set of half-waves of mains comprises 1 to 20 half-waves.
  • the reduced pulse duration is between half of the minimum pulse duration and minimum pulse duration.
  • the reduced pulse duration is in the range between 5 ⁇ s and 9 ⁇ s, preferably 7 ⁇ s, and the minimum pulse duration is at least 10 ⁇ s.
  • the control unit is configured to increase the pulse duration of the enabling signal pulses with each enabling signal pulse by a predefined pulse duration step until said minimum value of pulse duration is reached. So, in other words, starting at a reduced pulse duration starting value, the pulse duration is stepwise increased until said minimum value of pulse duration is reached.
  • the step width may be chosen such that said minimum value of pulse duration is reached as quick as possible without a significant generation of acoustic noise. Thereby, a return to the nominal range of pulse duration as soon as possible is achieved.
  • the control unit after reaching said minimum value of pulse duration, is configured to adapt the pulse duration of the enabling signal pulses according to the requested power. So, after performing the noise reduction routine, the control unit is driving the power stage in the normal power regulation mode, wherein the pulse duration is between minimum and maximum pulse duration value in order to power the induction element according to the power setting chosen by the user.
  • the invention relates to a method for operating an induction hob, the induction hob comprising a power stage with at least one switching element for enabling an alternating current flow through an induction element and a control unit providing an enabling signal comprising pulses with a variable pulse duration to the switching element for enabling said current flow through said induction element, wherein the pulse duration is changed between a minimum value and a maximum value in order to adjust the power provided to the induction element.
  • the pulse duration of a set of enabling signal pulses is reduced to a reduced pulse duration lower than said minimum value when starting the heating process in order to reduce acoustic noise.
  • Fig. 1 shows a schematic illustration of an induction hob 1 according to the invention.
  • the induction hob 1 may comprise multiple heating zones 2 preferably provided at a common hob plate. Each heating zone is correlated with at least one induction element placed beneath the hop plate.
  • the induction hob 1 further comprises a user interface 3 for receiving user input and/or providing information, specifically graphical information to the user.
  • the induction hob 1 may comprise at least one switching element associated with a respective induction element for enabling a current flow through said induction element.
  • the switching element may be controlled by an enabling signal, said enabling signal enabling a current flow through said induction element in order to induce eddy currents within the piece of cookware placed above the induction element.
  • Fig. 2 shows a schematic block diagram of an induction hob 1 being adapted to perform a noise reduction routine for reducing acoustic noise after starting a heating process.
  • the induction hob 1 comprises a power stage 10, a control unit 11 and a user interface 3, said user interface 3 being coupled with the control unit 11 in order to provide information to the user and/or to receive information from the user via the user interface 3. Furthermore, the induction hob 1 may comprise a bridge rectifier 13, said bridge rectifier 13 being coupled with the power stage 10 for providing electrical power to the induction element comprised within the power stage 10. The bridge rectifier 13 may be coupled with one or more phases of the mains supply network.
  • control unit 11 is coupled with the power stage 10 via a driver unit 12, said driver unit 12 being adapted to receive an enabling signal P comprising electrical pulses provided by the control unit 11, modify said received enabling signal P and provide a modified enabling signal P' to the power stage 10.
  • control unit 11 may be directly coupled with the power stage 10, i.e. may provide the enabling signal P directly to the power stage 10.
  • the control unit 11 is adapted to modify the pulse duration ⁇ P according to the requested power.
  • the requested power may be provided to the control unit 11 according to a power demand entered by a user at the user interface 3.
  • the pulse duration ⁇ P may vary between a minimum pulse duration ⁇ P min , which corresponds to a minimum of requested power, and a maximum pulse duration ⁇ P max , which corresponds to a maximum of requested power.
  • Said minimum pulse duration ⁇ P min and maximum pulse duration ⁇ P max may be chosen in order to guarantee a certain lifetime of a switching element enabling an alternating current flow through an induction element based on the enabling signal P.
  • control unit 11 is adapted to perform a noise reduction mechanism.
  • the pulse duration ⁇ P is lowered below the minimum pulse duration ⁇ P min after start-up of the power stage 10. Thereby, the acoustic noise can be significantly reduced.
  • Fig. 3 shows the driver unit 12, the power stage 10 and the bridge rectifier 13 in closer detail.
  • the driver unit 12 receives at input I1 the enabling signal P for enabling an alternating current flow through the power stage 10.
  • the driver unit 12 comprises an electrical circuitry configured to adapt the received enabling signal P according to the needs of the power stage 10. For example, the driver unit may amplify the received enabling signal P and/or may change the signal level of the enabling signal P by adding a certain offset voltage value to said received enabling signal P in order to derive a modified enabling signal P'.
  • Said modified electrical pulse P' may be provided to the gate of the switching element 20.
  • Said switching element 20 may be, for example, an IGBT.
  • the collector (node 23) of the switching element 20 may be coupled via a filtering circuitry (comprising one or more capacitors) to an oscillating circuit 25, said oscillating circuit 25 comprising the induction element 21, preferably constituted by an induction coil, and a capacitor 22.
  • the power stage 10 may comprise quasi-resonant power stage architecture.
  • the induction element 21 may be coupled with the bridge rectifier 13 in order to power the oscillating circuit 25 by the mains supply network.
  • the capacitor 22 is charged, i.e. electric energy provided by the bridge rectifier 13 is stored in the capacitor 22.
  • the electric voltage Vcap at node 24 is the rising.
  • the electric voltage Vcap of node 24 may be up to 1.41* V mains , wherein V mains is the mains voltage.
  • the electric voltage Vcap of node 24 is correlated with the amount of electric energy stored in the capacitor 22 which may be used for providing current flow through the induction element 21.
  • the pulse duration ⁇ P of the enabling signal P may be indicative for the amount of electric charge which will be used for creating said current flow through the induction element 21.
  • the Applicant found out that when driving the switching element below said threshold pulse duration or below said minimum pulse duration ⁇ P min for a limited period of time after starting the power stage 10, the lifetime of the switching element 21 is not or not significantly reduced.
  • the normal range of pulse duration ⁇ P may be 10 ⁇ s to 22 ⁇ s, wherein the lower value corresponds to the minimum power setting and the upper value corresponds to the maximum power setting.
  • the pulse duration ⁇ P may be lowered to a reduced pulse duration ⁇ P red wherein 0.5 ⁇ P max ⁇ ⁇ P red ⁇ ⁇ P min .
  • the reduced pulse duration ⁇ P red is in the range between 5 ⁇ s and 9 ⁇ s, preferably 7 ⁇ s.
  • Said reduction of pulse duration ⁇ P may be only obtained for a short period of time.
  • the pulse duration reduction may be obtained for a certain number of half wave cycles of the mains supply voltage provided by the bridge rectifier 13.
  • the pulse duration reduction may be obtained for 1 to 20 half wave cycles of the mains supply voltage.
  • the pulse duration ⁇ P can be stepwise increased without producing more acoustic noise.
  • the pulse duration ⁇ P may be increased by a certain step width every half wave cycle after starting the power stage 10.
  • the step width may be in the range of 0.2 ⁇ s to 1 ⁇ s, specifically 0.5 ⁇ s.
  • the choosen step width may depend on the reduction ratio, i.e. the ratio by which the reduced pulse duration ⁇ P red is lower than the minimum pulse duration ⁇ P min .
  • the pulse duration ⁇ P may be increased as long as the minimum power duration ⁇ P min (which corresponds to the minimum power setting) is reached.
  • control unit 11 may adapt the power duration ⁇ P according to the requested power provided by the user via the user interface 3 in order to heat the piece of cookware placed above the induction element 21 according to the chosen power setting.
  • Fig. 4 and 5 show signal diagrams of the enabling signal P, the capacitor voltage Vcap at node 24, the collector voltage Vc at node 23 and a trigger signal TS causing the generation of the next pulse of the enabling signal P.
  • the signal illustrations of the enabling signal P and the trigger signal TS are shifted against the collector voltage Vc and the capacitor voltage Vcap for the sake of a better recognisability.
  • fig. 5 shows the signals following on the signals of fig. 4 .
  • the pulse duration is increasing with every occurrence of a further enabling signal pulse, wherein the step width for increasing the pulse duration ⁇ P of the enabling signal P is 0.5 ⁇ s in the present embodiment.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Induction Heating Cooking Devices (AREA)
EP14185260.8A 2014-09-18 2014-09-18 Plaque de cuisson à induction et procédé pour faire fonctionner une telle plaque Withdrawn EP2999304A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP14185260.8A EP2999304A1 (fr) 2014-09-18 2014-09-18 Plaque de cuisson à induction et procédé pour faire fonctionner une telle plaque
EP15176589.8A EP2999307B1 (fr) 2014-09-18 2015-07-14 Plaque de cuisson à induction et procédé pour faire fonctionner une telle plaque

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP14185260.8A EP2999304A1 (fr) 2014-09-18 2014-09-18 Plaque de cuisson à induction et procédé pour faire fonctionner une telle plaque

Publications (1)

Publication Number Publication Date
EP2999304A1 true EP2999304A1 (fr) 2016-03-23

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EP14185260.8A Withdrawn EP2999304A1 (fr) 2014-09-18 2014-09-18 Plaque de cuisson à induction et procédé pour faire fonctionner une telle plaque
EP15176589.8A Active EP2999307B1 (fr) 2014-09-18 2015-07-14 Plaque de cuisson à induction et procédé pour faire fonctionner une telle plaque

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EP15176589.8A Active EP2999307B1 (fr) 2014-09-18 2015-07-14 Plaque de cuisson à induction et procédé pour faire fonctionner une telle plaque

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2999307B1 (fr) 2014-09-18 2018-10-24 Electrolux Appliances Aktiebolag Plaque de cuisson à induction et procédé pour faire fonctionner une telle plaque
EP3582586A1 (fr) 2018-06-16 2019-12-18 Electrolux Appliances Aktiebolag Procédé pour commander une zone de cuisson d'une table de cuisson par induction

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2108786A (en) * 1981-11-05 1983-05-18 Sanyo Electric Co Induction heating apparatus
JP2008204884A (ja) * 2007-02-22 2008-09-04 Matsushita Electric Ind Co Ltd 誘導加熱装置
JP2009295392A (ja) * 2008-06-04 2009-12-17 Toshiba Home Technology Corp 電磁誘導加熱装置
WO2013061595A1 (fr) * 2011-10-28 2013-05-02 パナソニック株式会社 Dispositif de chauffage à induction

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4385212A (en) 1981-10-05 1983-05-24 Bell Telephone Laboratories Incorporated Expandable communication terminal housing
FR3000361B1 (fr) 2012-12-20 2014-12-26 Fagorbrandt Sas Procede et disposiif d'alimentation en puissance des moyens d'induction
EP2999304A1 (fr) 2014-09-18 2016-03-23 Electrolux Appliances Aktiebolag Plaque de cuisson à induction et procédé pour faire fonctionner une telle plaque

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2108786A (en) * 1981-11-05 1983-05-18 Sanyo Electric Co Induction heating apparatus
JP2008204884A (ja) * 2007-02-22 2008-09-04 Matsushita Electric Ind Co Ltd 誘導加熱装置
JP2009295392A (ja) * 2008-06-04 2009-12-17 Toshiba Home Technology Corp 電磁誘導加熱装置
WO2013061595A1 (fr) * 2011-10-28 2013-05-02 パナソニック株式会社 Dispositif de chauffage à induction

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2999307B1 (fr) 2014-09-18 2018-10-24 Electrolux Appliances Aktiebolag Plaque de cuisson à induction et procédé pour faire fonctionner une telle plaque
EP3582586A1 (fr) 2018-06-16 2019-12-18 Electrolux Appliances Aktiebolag Procédé pour commander une zone de cuisson d'une table de cuisson par induction
WO2019238447A1 (fr) 2018-06-16 2019-12-19 Electrolux Appliances Aktiebolag Procédé destiné à la commande d'une zone de cuisson d'une table de cuisson à induction
US11825585B2 (en) 2018-06-16 2023-11-21 Electrolux Appliances Aktiebolag Method for controlling a cooking zone of an induction cooking hob

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Publication number Publication date
EP2999307B1 (fr) 2018-10-24
EP2999307A1 (fr) 2016-03-23

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